New state-of-the-art trains are set to replace Greater Anglia services in Suffolk this year - but potential delays could mean older trains will still be in use on some routes.

The Bombardier Aventra trains being built at Derby are due to start arriving in East Anglia in the autumn and should start taking over suburban services at the end of the year.

Some 111 new Aventra trains will be serving commuter lines from London to Colchester, Ipswich, Clacton, Cambridge and Southend.

But similar trains that have been delivered to London Overground from 2017 have still not entered passenger service after unexpected issues had arisen from testing on the tracks around the capital.

A Greater Anglia said: “At the moment we are not facing any delays but we are watching the situation and are in regular contact with Bombardier.”

Meanwhile in Norfolk, test runs of new bi-mode trains, made by Swiss company Stadler, had taken place last week from Norwich to Colchester and Ipswich and from Norwich to Thetford, as well as on the Norwich to Great Yarmouth line.

Night-time testing will also continue in February and March between Norwich and Diss as technicians check the trains’ pantographs, which draw power from the overhead wires, and monitor the wheel sets – known as bogies.

The bi-mode trains switch between electric and diesel power and have environmentally-friendly features.